U.S. patent application number 13/641794 was filed with the patent office on 2013-02-14 for vacuum capacitor.
This patent application is currently assigned to MEIDENSHA CORPORATION. The applicant listed for this patent is Toshimasa Fukai, Kaoru Kitakizaki, Yuichi Nishikiori, Eiichi Takahashi, Toshinori Tatsumi. Invention is credited to Toshimasa Fukai, Kaoru Kitakizaki, Yuichi Nishikiori, Eiichi Takahashi, Toshinori Tatsumi.
Application Number | 20130038978 13/641794 |
Document ID | / |
Family ID | 44834041 |
Filed Date | 2013-02-14 |
United States Patent
Application |
20130038978 |
Kind Code |
A1 |
Takahashi; Eiichi ; et
al. |
February 14, 2013 |
VACUUM CAPACITOR
Abstract
The present invention can easily adjust capacitance of a vacuum
capacitor while maintaining a vacuum state in a vacuum chamber of
the vacuum capacitor. A fixed electrode 4 is formed by arranging a
plurality of flat electrode members 5 in layers at a certain
distance in an axial direction of a vacuum chamber 1b. A movable
electrode 7 is formed by arranging a plurality of flat electrode
members 8 in layers at a certain distance in the axial direction of
the vacuum chamber 1b and fixing the electrode members 8 to a
movable electrode shaft 9. By rotation of the movable electrode
shaft 9, each electrode member 8 is inserted into and extracted
from a gap between the electrode members 5 of the fixed electrode 4
in noncontact with the electrode members 5 of the fixed electrode
4. A magnetic flux receiving portion 106b is fixed to a seal member
102 side of a disk member 106a that is provided at the movable
electrode shaft 9. A magnetic flux generating unit 104 provided at
a capacitance control unit 14 is arranged in a direction parallel
to the movable electrode shaft 9 with respect to the magnetic flux
receiving portion 106b. By rotating the capacitance control unit 14
also rotating the magnetic flux receiving portion 106b by magnetic
attraction of the magnetic flux generating unit 104, an overlap
area of the movable electrode 7 with respect to the fixed electrode
4 is changed, capacitance is then adjusted.
Inventors: |
Takahashi; Eiichi;
(Numazu-shi, JP) ; Fukai; Toshimasa; (Sunto-gun,
JP) ; Tatsumi; Toshinori; (Numazu-shi, JP) ;
Nishikiori; Yuichi; (Numazu-shi, JP) ; Kitakizaki;
Kaoru; (Saitama-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Takahashi; Eiichi
Fukai; Toshimasa
Tatsumi; Toshinori
Nishikiori; Yuichi
Kitakizaki; Kaoru |
Numazu-shi
Sunto-gun
Numazu-shi
Numazu-shi
Saitama-shi |
|
JP
JP
JP
JP
JP |
|
|
Assignee: |
MEIDENSHA CORPORATION
|
Family ID: |
44834041 |
Appl. No.: |
13/641794 |
Filed: |
March 28, 2011 |
PCT Filed: |
March 28, 2011 |
PCT NO: |
PCT/JP2011/057646 |
371 Date: |
October 17, 2012 |
Current U.S.
Class: |
361/279 |
Current CPC
Class: |
H01G 5/013 20130101;
H01G 5/06 20130101 |
Class at
Publication: |
361/279 |
International
Class: |
H01G 5/013 20060101
H01G005/013 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 19, 2010 |
JP |
2010-095786 |
Claims
1. A vacuum capacitor, in which a fixed electrode formed from a
plurality of electrode members is arranged and a movable electrode
formed from a plurality of electrode members is arranged in a gap
formed between the electrode members of the fixed electrode in a
vacuum casing, and whose capacitance appearing between the movable
electrode and the fixed electrode is varied by rotating a movable
electrode shaft that supports the movable electrode, the vacuum
capacitor comprising: a magnetic flux receiving portion that
rotates the movable electrode shaft in the vacuum casing; a
magnetic flux generating unit that is arranged in a direction
parallel to the movable electrode shaft with respect to the
magnetic flux receiving portion outside the vacuum casing and
rotates the magnetic flux receiving portion by magnetic attraction;
and a capacitance control unit that rotates the magnetic flux
generating unit.
2. A vacuum capacitor comprising: a vacuum casing formed by closing
both opening end sides of an insulation tube body by respective
seal members; a fixed electrode formed by arranging a plurality of
flat electrode members in layers at a certain distance in an axial
direction of the vacuum casing in the vacuum casing; a movable
electrode formed by arranging a plurality of flat electrode members
in layers at a certain distance in the axial direction of the
vacuum casing in the vacuum casing, and fixed to a movable
electrode shaft that extends in the axial direction of the vacuum
casing and is rotatably supported in the vacuum casing, and by
rotation of the movable electrode shaft, the each electrode member
of the movable electrode being inserted into and extracted from a
gap between the electrode members of the fixed electrode and
alternately overlapping the electrode member of the fixed electrode
with the each electrode member of the movable electrode in
noncontact with the electrode members of the fixed electrode; a
magnetic flux receiving portion fixed to the movable electrode
shaft in the vacuum casing and receiving magnetic flux from the
outside of the vacuum casing through the seal member; a magnetic
flux generating unit that is arranged in a direction parallel to
the movable electrode shaft with respect to the magnetic flux
receiving portion outside the vacuum casing and generates the
magnetic flux; and a capacitance control unit having the magnetic
flux generating unit and rotatably supported outside the seal
member, and by rotating the capacitance control unit also rotating
the magnetic flux receiving portion by magnetic attraction of the
magnetic flux, an overlap area of the movable electrode with
respect to the fixed electrode being changed, and capacitance being
adjustable.
3. The vacuum capacitor as claimed in claim 1, wherein: a bearing
of the movable electrode shaft is a plain bearing.
4. The vacuum capacitor as claimed in claim 1, wherein: each area
of the electrode members is smaller than an area in a cross-section
direction of an inside of the vacuum casing, and by the rotation of
the movable electrode shaft which is within one revolution, the
capacitance is variable within a range from a minimum capacitance
value to a maximum capacitance value.
5. The vacuum capacitor as claimed in claim 2, wherein: the movable
electrode shaft is rotatably supported with the movable electrode
shaft sandwiched between the seal members provided at the both
opening ends of the insulation tube body.
6. The vacuum capacitor as claimed in claim 2, wherein: a bearing
of the movable electrode shaft is a plain bearing.
7. The vacuum capacitor as claimed in claim 2, wherein: each area
of the electrode members is smaller than an area in a cross-section
direction of an inside of the vacuum casing, and by the rotation of
the movable electrode shaft which is within one revolution, the
capacitance is variable within a range from a minimum capacitance
value to a maximum capacitance value.
Description
TECHNICAL FIELD
[0001] The present invention relates to a vacuum capacitor applied,
for example, in a high-frequency power supply circuit used in a
semiconductor manufacturing system, and relates to a variable type
vacuum capacitor in which a fixed electrode and a movable electrode
are arranged in a vacuum casing and whose capacitance value is
variable.
BACKGROUND ART
[0002] Many vacuum capacitors are applied, for example, in the
high-frequency power supply circuit used in the semiconductor
manufacturing system. When broadly categorizing the vacuum
capacitor by its structure, there are two types of vacuum
capacitors of a fixed type vacuum capacitor whose capacitance value
is fixed and a variable type vacuum capacitor (e.g. Patent
Documents 1.about.3) whose capacitance value is variable.
[0003] As an example of the variable type vacuum capacitor, a
capacitor, in which a fixed electrode and a movable electrode are
arranged in a vacuum casing and whose capacitance is varied by
moving the movable electrode while maintaining a vacuum state in
the vacuum casing using bellows etc., is known. As the vacuum
casing, an insulation tube body made of insulation material such as
ceramic material and seal members made of material of copper etc.
are provided, and each opening end side of the insulation tube body
is closed by the seal member, then the vacuum casing is formed.
Each seal member is formed mainly from a tube member that is
provided at the opening end side of the insulation tube body and a
cover member that closes the tube member.
[0004] The fixed electrode is formed from a plurality of
substantially cylindrical electrode members whose diameters are
different from each other and which are arranged concentrically
(for instance, the cylindrical electrode members are arranged at a
certain distance). The fixed electrode is provided at one
(hereinafter, called one side seal member, and the other is called
the other side seal member) of the seal members inside the vacuum
casing. The movable electrode is, same as the fixed electrode,
formed from a plurality of substantially cylindrical electrode
members whose diameters are different from each other and which are
arranged concentrically (for instance, the cylindrical electrode
members are arranged at a certain distance). The movable electrode
is arranged inside the vacuum casing so that each electrode member
of the movable electrode can be inserted into and extracted from a
gap between the electrode members of the fixed electrode (the
electrode members of the movable electrode are arranged in a
staggered configuration so as to be inserted into and extracted
from the gap between the electrode members of the fixed electrode
and alternately overlap the electrode member of the fixed
electrode) with the each electrode member of the movable electrode
in noncontact with the electrode members of the fixed electrode.
This movable electrode is supported by a movable electrode shaft
that moves in an axial direction of the vacuum casing (that moves
so as to be able to adjust the extent of the insertion/extraction
of the movable electrode with respect to the fixed electrode).
[0005] The movable electrode shaft is formed, for instance, from a
supporting member (hereinafter, called a movable supporting member)
to support the movable electrode and a rod (hereinafter, called a
movable rod) that extends from a back surface side of the movable
supporting member (e.g. from a surface side of the movable
supporting member which faces the other side seal member) to the
axial direction of the vacuum casing. This movable electrode shaft
is slidably supported (for instance, the movable electrode shaft is
slidably supported so that the movable rod can slide in the axial
direction of the vacuum casing), for instance, through a bearing
member provided at the vacuum casing (e.g. a bearing member fixed
at the middle of the cover member).
[0006] To adjust the capacitance by moving the movable electrode
shaft in the axial direction of the vacuum casing, for example, a
member (hereinafter, called a capacitance control unit) that is
connected to one end side of the movable rod and rotates by a drive
source such as a motor is used. This capacitance control unit is
screwed onto the one end side of the movable rod (for example, a
female screw part formed at the capacitance control unit is screwed
onto the male screw part formed at the one end side of the movable
rod), then connects with the movable rod. The capacitance control
unit that can rotate by the drive source such as the motor is
employed. Further, the capacitance control unit is supported
rotatably with respect to the vacuum casing etc. through a
supporting member formed from e.g. a thrust bearing.
[0007] The bellows is a bellows metal member having
expansion/contraction characteristics. The bellows serves as a part
of a current path of the vacuum capacitor, and divides the inside
of the vacuum casing into a vacuum chamber and an atmospheric
chamber. By virtue of this bellows, the movable electrode, the
movable supporting member and the movable rod can move in the axial
direction of the vacuum casing with a space enclosed by the fixed
electrode, the movable electrode and the bellows in the vacuum
casing kept airtight as the vacuum chamber (with the space being a
vacuum state). For example, one side edge of the bellows is
connected to an inner wall side of the other side seal member at
the bearing member side, and the other side edge of the bellows is
connected to the movable supporting member etc.
[0008] Here, with regard to the connection of the bellows, for
instance, vacuum brazing is employed. Further, as the bellows,
there are some bellows having different structures. For example,
bellows having a structure in which the other side edge of the
bellows is connected to a surface of the movable rod and bellows
having a double bellows structure (e.g. the structure in which
stainless bellows and copper bellows are combined) are known.
[0009] In the vacuum capacitor having such structure described
above, by rotating the capacitance control unit by the drive source
such as the motor, rotational motion by the rotation of the
capacitance control unit is converted to axial direction motion of
the movable electrode shaft, then an overlap area between the fixed
electrode and the movable electrode is varied in response to a
movement amount of the movable electrode shaft. At this time, the
bellows expands or contracts in accordance with the movement of the
movable rod.
[0010] With this, when voltage is applied to the fixed electrode
and the movable electrode and the bellows expands or contracts, the
overlap area between the fixed electrode and the movable electrode
changes, and a value of capacitance appearing between the both
electrodes is seamlessly changed, then the impedance adjustment is
made. Regarding high frequency current for the high-frequency
apparatus of a case using such vacuum capacitor, the high frequency
current flows from the one side seal member to the other side seal
member through the bellows and the capacitance between the facing
electrodes (between the fixed electrode and the movable
electrode).
CITATION LIST
Patent Document
[0011] Patent Document 1: Japanese Patent Application Publication
No. JP6-241237 [0012] Patent Document 2: Japanese Patent
Application Publication No. JP2005-180535 [0013] Patent Document 3:
Japanese Patent Application Publication No. JP8-45785 [0014] Patent
Document 4: Japanese Patent Application Publication No.
JP11-158604
SUMMARY OF THE INVENTION
Technical Problem
[0015] As described above, in the case where the capacitance is
varied by moving the movable electrode shaft while maintaining the
vacuum state of the vacuum chamber in the variable type vacuum
capacitor, it can be read that the metal member having
expansion/contraction properties, such as the bellows, is needed
(to divide the inside of the vacuum casing into a vacuum chamber
and an atmospheric chamber). Also it can be read that there is a
need to move the movable electrode shaft in the axial direction of
the vacuum casing by the rotational motion of the capacitance
control unit.
[0016] That is to say, when moving the movable electrode shaft, it
is required that the movement of the movable electrode shaft be
done against a pressure occurring at a division wall (the bellows,
the insulation tube body and the one side seal member, etc.) of the
vacuum chamber. In addition, since a high mechanical stress is
imposed on the metal member such as the bellows at every repetition
of the expansion/contraction, the metal member is likely to be
broken, and a life of the vacuum capacitor (the vacuum chamber
etc.) also becomes shorter. Especially when the bellows serves as
the current path, temperature of the bellows becomes high due to
heat generation upon the application of the current. Thus the life
of the vacuum capacitor becomes even shorter.
[0017] In the case where the rotational motion by the capacitance
control unit is converted to the axial direction motion of the
movable electrode shaft, for instance, the structure in which the
capacitance control unit and the movable electrode shaft (the
movable rod etc.) are connected by the screw-connection is
employed. However, because a plurality of rotational motion of the
capacitance control unit is required, it takes much time to adjust
the capacitance, it is therefore difficult to instantaneously
change the capacitance value.
Solution to Problem
[0018] In order to solve the above problems, according to one
aspect of the present invention, a vacuum capacitor, in which a
fixed electrode formed from a plurality of electrode members is
arranged and a movable electrode formed from a plurality of
electrode members is arranged in a gap formed between the electrode
members of the fixed electrode in a vacuum casing, and whose
capacitance appearing between the movable electrode and the fixed
electrode is varied by rotating a movable electrode shaft that
supports the movable electrode, the vacuum capacitor comprises: a
magnetic flux receiving portion that rotates the movable electrode
shaft in the vacuum casing; a magnetic flux generating unit that is
arranged in a direction parallel to the movable electrode shaft
with respect to the magnetic flux receiving portion outside the
vacuum casing and rotates the magnetic flux receiving portion by
magnetic attraction; and a capacitance control unit that rotates
the magnetic flux generating unit.
[0019] In order to solve the above problems, according to another
aspect of the present invention, a vacuum capacitor comprises: a
vacuum casing formed by closing both opening end sides of an
insulation tube body by respective seal members; a fixed electrode
formed by arranging a plurality of flat electrode members in layers
at a certain distance in an axial direction of the vacuum casing in
the vacuum casing; a movable electrode formed by arranging a
plurality of flat electrode members in layers at a certain distance
in the axial direction of the vacuum casing in the vacuum casing,
and fixed to a movable electrode shaft that extends in the axial
direction of the vacuum casing and is rotatably supported in the
vacuum casing, and by rotation of the movable electrode shaft, the
each electrode member of the movable electrode being inserted into
and extracted from a gap between the electrode members of the fixed
electrode and alternately overlapping the electrode member of the
fixed electrode with the each electrode member of the movable
electrode in noncontact with the electrode members of the fixed
electrode; a magnetic flux receiving portion fixed to the movable
electrode shaft in the vacuum casing and receiving magnetic flux
from the outside of the vacuum casing through the seal member; a
magnetic flux generating unit that is arranged in a direction
parallel to the movable electrode shaft with respect to the
magnetic flux receiving portion outside the vacuum casing and
generates the magnetic flux; and a capacitance control unit having
the magnetic flux generating unit and rotatably supported outside
the seal member. And by rotating the capacitance control unit also
rotating the magnetic flux receiving portion by magnetic attraction
of the magnetic flux, an overlap area of the movable electrode with
respect to the fixed electrode is changed, and capacitance is
adjustable.
[0020] In the above vacuum capacitor, it is preferable that a
bearing of the movable electrode shaft ne a plain bearing.
[0021] Further, in the above vacuum capacitor to solve the above
problems, each area of the electrode members is smaller than an
area in a cross-section direction of an inside of the vacuum
casing, and by the rotation of the movable electrode shaft which is
within one revolution, the capacitance is variable within a range
from a minimum capacitance value to a maximum capacitance
value.
[0022] Furthermore, in the above vacuum capacitor to solve the
above problems, the movable electrode shaft is rotatably supported
with the movable electrode shaft sandwiched between the seal
members provided at the both opening ends of the insulation tube
body.
EFFECTS OF THE INVENTION
[0023] As described above, according to the present invention,
there is no need to use the bellows, and it is possible to
contribute to the prolongation of the life of the vacuum capacitor.
In addition, the instantaneous change of the capacitance can be
achieved by the rotation of the movable electrode.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] FIG. 1 is a perspective view of a longitudinal cross section
of part of a vacuum capacitor, according to the present
embodiment.
[0025] FIG. 2 is a perspective exploded view of a part of a fixed
electrode for explaining an example of the fixed electrode arranged
in a vacuum chamber, according to the present embodiment.
[0026] FIG. 3 is a schematic view for explaining an example of a
movable electrode arranged in the vacuum chamber, according to the
present embodiment.
[0027] FIG. 4 is a schematic view for explaining an example of
change of capacitance by insertion/extraction of the fixed
electrode and the movable electrode, according to the present
embodiment.
[0028] FIG. 5 is a schematic view for explaining an example of
change of the capacitance by the insertion/extraction of the fixed
electrode and the movable electrode, according to the present
embodiment.
[0029] FIG. 6 is a schematic view for explaining an example of a
supporting structure of a capacitance control unit, according to
the present embodiment.
[0030] FIG. 7 is a schematic view for explaining an example of a
structure in which magnetic flux .PHI. of a magnetic flux
generating unit is received by a magnetic flux receiving portion,
according to the present embodiment.
[0031] FIG. 8 is a schematic view for explaining the example of the
structure in which the magnetic flux .phi. of the magnetic flux
generating unit is received by the magnetic flux receiving portion,
according to the present embodiment.
EMBODIMENTS FOR CARRYING OUT THE INVENTION
[0032] In the following description, an embodiment of a variable
type vacuum capacitor according to the present invention will be
explained with reference to FIGS. 1 to 8.
[0033] FIG. 1 is a perspective view of a longitudinal cross section
of part of the variable type vacuum capacitor.
[0034] A vacuum casing 1 is formed by providing an insulation tube
body 1a made of insulation material such as ceramic material and
one side seal member 2 and the other side seal member 102 each made
of material of copper etc. and closing both opening end sides of
the insulation tube body 1a by the seal members 2 and 102. The
vacuum casing 1 has a vacuum chamber 1b inside the vacuum casing
1.
[0035] The one side seal member 2 in FIG. 1 has a tube member 2a
that is provided at the one opening end side (in FIG. 1, at a lower
side) of the insulation tube body 1a and a cover member 2b that
closes the tube member 2a. Further, a groove portion 2c (three
groove portions in FIG. 2) to support an after mentioned fixed
electrode shaft 6 so as to stand is formed at an outer
circumferential edge portion on an inner surface of the cover
member 2b in the vacuum chamber 1b. A groove portion 2d to mount an
after mentioned guide 11c is formed at the middle of the cover
member 2b in the vacuum chamber 1b.
[0036] The other side seal member 102 in FIG. 1 has a cover member
102b and a vacuum partition plate 102a that is provided on an outer
peripheral surface of a lower end portion of the cover member 102b.
An outer circumferential portion of the vacuum partition plate 102a
is fixed, by brazing in the vacuum condition, to a seal portion
112b that is formed at an inner circumferential portion of a tube
member 112a provided at the other opening end side (in FIG. 1, at
an upper side) of the insulation tube body 1a. A ring-shaped groove
portion 112e that is a movement passage for an after mentioned
magnetic flux generating unit 104 is defined by a space enclosed by
these tube member 112a, vacuum partition plate 102a and an outer
circumference of the cover member 102b.
[0037] A groove portion 102f to rotatably support an after
mentioned movable electrode shaft 9 is formed at the middle on an
inner surface of the cover member 102b in the vacuum chamber 1b.
Further, a cover member side guide shaft 102i that is loosely
inserted in a control member side guide shaft 14b of an after
mentioned capacitance control unit 14 through a bearing (an oilless
bearing etc.) 14d is formed on a surface of the cover member 102b
which is opposite to the surface where the groove portion 102f is
formed. Then the capacitance control unit 14 is rotatably supported
by the cover member side guide shaft 102i.
[0038] A fixed electrode 4 is formed by arranging a plurality of
flat electrode members 5 in layers at a certain distance (that is
greater than a thickness of an electrode member 8 of a movable
electrode 7) in an axial direction of the vacuum chamber 1b (in a
direction of a line connecting the seal members 2 and 102). The
fixed electrode 4 is fixedly supported through the fixed electrode
shaft 6.
[0039] In FIG. 1, two split fixed electrode shafts 6a and 6b are
used. One fixed electrode shaft 6a stands on the cover member 2b
and is fixed to the cover member 2b, and is electrically connected
to a lead connection terminal (not shown) provided at an outer side
of the cover member 2b outside the vacuum chamber 1b. The other
fixed electrode shaft 6b is fixedly supported by a lead connection
terminal 6c that penetrates and is positioned at the middle, in a
longitudinal direction, of the insulation tube body 1a. The fixed
electrode shaft 6b is electrically connected to the lead connection
terminal 6c. With this, the fixed electrode 4 is divided into an
electrode (hereinafter, called one side fixed electrode) positioned
at the one side seal member 2 side and electrically connected to
the lead connection terminal (not shown) and an electrode
(hereinafter, called the other side fixed electrode) positioned at
the other side seal member 102 side and electrically connected to
the lead connection terminal 6c.
[0040] The movable electrode 7 is formed by arranging a plurality
of flat electrode members 8 in layers at a certain distance (that
is greater than a thickness of the electrode member 5 of the fixed
electrode 4) in the axial direction of the vacuum chamber 1b, same
as the fixed electrode 4. The electrode members 8 are arranged in a
staggered configuration inside the vacuum chamber 1b so that each
electrode member 8 of the movable electrode 7 can be inserted into
and extracted from a gap between the electrode members 5 of the
fixed electrode 4 and alternately overlap the electrode member 5
with the each electrode member 8 of the movable electrode 7 in
noncontact with the electrode members 5 of the fixed electrode 4.
The movable electrode 7 is rotatably supported through the movable
electrode shaft 9 that extends in the axial direction (e.g. in FIG.
1, on a shaft center) of the vacuum chamber 1b. The movable
electrode shaft 9 in FIG. 1 is provided with insulative shafts 9a
and 9b at both ends of the movable electrode shaft 9. The
insulative shaft 9a and the insulative shaft 9b are rotatably
supported through a penetration hole 11b and the groove portion
102f respectively.
[0041] As described above, by sandwiching and rotatably supporting
both end surfaces of the movable electrode shaft 9 by the seal
members 2 and 102 that close the both opening ends of the
insulation tube body 1a, complete vacuum sealing can be achieved
without having to provide shaft seals etc. at contact portions
between the movable electrode shaft 9 and the casing.
[0042] Here, the movable electrode 7 in FIG. 1 is not electrically
connected to an outside of the vacuum casing 1. The movable
electrode 7 is divided into an electrode (hereinafter, called one
side movable electrode) positioned at the one side seal member 2
side and overlapping and inserted into and extracted from the one
side fixed electrode and an electrode (hereinafter, called the
other side movable electrode) positioned at the other side seal
member 102 side and overlapping and inserted into and extracted
from the other side fixed electrode.
[0043] That is, a capacitance C in the vacuum casing 1 is a total
capacitance of capacitance (hereinafter, called one side
capacitance) by an overlap area between the one side fixed
electrode and the one side movable electrode and capacitance
(hereinafter, called the other side capacitance) by an overlap area
between the other side fixed electrode and the other side movable
electrode. Therefore, configuration of the vacuum casing 1 is the
one that connects two capacitors in series.
[0044] Here, in a case where the fixed electrode 4 is divided into
a plurality of fixed electrodes and each fixed electrode is
electrically connected to the outside of the vacuum casing 1
through the respective lead connection terminals, configuration in
which, same as the divided fixed electrode 4, the movable electrode
7 and the movable electrode shaft 9 are also divided respectively
into a plurality of movable electrodes and a plurality of movable
electrode shafts (for instance, the movable electrode shaft 9 is
divided using the insulator at a part of the movable electrode
shaft 9) and a plurality of these capacitors are connected in
series is conceivable. Further, in a case where the insulation tube
body 1a is divided into a plurality of insulation tube bodies,
configuration, in which at least one of the respective lead
connection terminals is disposed between the divided insulation
tube bodies la, is conceivable.
[0045] Regarding a supporting structure of the movable electrode
shaft 9 at the one side seal member 2 side, as long as the
structure is a structure that can maintain the vacuum state of the
vacuum chamber 1b, various kinds of structures can be applied. For
example, as shown in FIG. 1, it could be a structure in which the
guide 11c provided with the penetration hole (having such shape
that one end side of the movable electrode shaft 9 (in FIG. 1, the
insulative shaft 9a) can penetrate) 11b is provided so as to cover,
from the inside of the vacuum chamber 1b, an adjustment diaphragm
11a that is provided on a bottom of the groove portion 2d. Then,
the one end side of the movable electrode shaft 9 penetrates the
penetration hole 11b of the guide 11c, and the one end side is
supported by the adjustment diaphragm 11a. In the case of this
structure, force by press-deformation of the adjustment diaphragm
11a acts on the one end side of the movable electrode shaft 9 from
the one end side touching the adjustment diaphragm 11a to the other
end side of the movable electrode shaft 9 (in a direction of the
other side seal member 102).
[0046] Furthermore, in a case where a hole 11d that communicates
with the outside of the vacuum casing 1 is formed in the groove
portion 2d, the adjustment diaphragm 11a is press-deformed in
accordance with a difference between an atmospheric pressure of the
outside of the vacuum casing 1 and a vacuum pressure of the vacuum
chamber 1b. That is, the force that press-deforms the adjustment
diaphragm 11a from the outside of the vacuum casing 1 to a
direction of the inside of the vacuum chamber 1b acts on the
adjustment diaphragm 11a by the pressure difference between the
outside of the vacuum casing 1 and the vacuum chamber 1b, and the
force of this press-deformation adds to the movable electrode shaft
9. The movable electrode shaft 9 is therefore supported while being
pressed in the direction of the other side seal member 102.
[0047] Moreover, in a case where configuration, in which one end
surface side of the movable electrode shaft 9 is flat as shown in
FIG. 1 and a portion 1e of the adjustment diaphragm 11a which
touches the movable electrode shaft 9 is formed into a pointed
shape then a part of the one end surface of the movable electrode
shaft 9 is supported at a point by the portion 11e, is employed,
for instance, a contact area is small as compared with a case where
an entire surface of the one end surface of the movable electrode
shaft 9 is supported. As a consequence, a rotation resistance of
the movable electrode shaft 9 can be reduced. In addition, also in
a case where configuration, in which the portion 11e touching the
movable electrode shaft 9 is not formed into the pointed shape but
formed into a flat shape and the end surface of the movable
electrode shaft 9 is formed into a pointed shape then the end
surface touches the portion 11e at this apex, is employed, the same
effect can be gained. That is, as long as the configuration is the
one in which either one side of the movable electrode shaft 9 and
the vacuum chamber 1b inner wall that faces the movable electrode
shaft 9 has a supporting portion that supports the other side at
one point, the rotation resistance can be reduced.
[0048] A magnetic drive plate (a magnetic drive unit) 106 is
provided at the other side seal member 102 side of the movable
electrode shaft 9 in the vacuum chamber 1b and rotates with the
movable electrode shaft 9. The magnetic drive plate 106 receives
magnetic flux .PHI. of the after mentioned magnetic flux generating
unit 104. For example, the magnetic drive plate 106 is made of
ferromagnetic material such as iron and nickel. As shown in FIG. 1,
the magnetic drive plate 106 has a disk member 106a that is
supported by penetration of the movable electrode shaft 9 and a
magnetic flux receiving portion 106b that is provided on a surface
of the disk member 106a which faces the vacuum partition plate
102a.
[0049] The capacitance control unit 14 is provided with the
magnetic flux generating unit 104 through a magnetic flux
generating unit fixing guide 103, and is rotatably supported by the
cover member side guide shaft 102i of the other side seal member
102. For instance, as shown in FIG. 1, the capacitance control unit
14, having a disk member 14a that is supported rotatably with
respect to the cover member 102b through the annular control member
side guide shaft 14b and the magnetic flux generating unit 104 that
is provided at an outer circumferential edge portion on an inner
surface of the disk member 14a in the vacuum chamber 1b and moves
in the groove portion 112e with the rotation of the disk member
14a, is used. This magnetic flux generating unit 104 could be
formed from, for instance, a permanent magnet 104 having N pole and
S pole and the magnetic flux generating unit fixing guide 103 that
holds the permanent magnet 104. For instance, the magnetic flux
generating unit 104 is fixed to the disk member 14a using
connecting means 13c such as a screw.
[0050] In the vacuum capacitor shown in FIG. 1, the movable
electrode shaft 9, the magnetic flux receiving portion 106b and the
capacitance control unit 14 (the magnetic flux generating unit 104)
rotate in the same direction. Regarding each structure in the
vacuum chamber 1b, for example, the adjustment diaphragm 11a, the
electrode member 5 and a spacer 5b and the fixed electrode shaft 6
which belong to the fixed electrode 4, and the electrode member 8
and a spacer 8b and the movable electrode shaft 9 which belong to
the movable electrode 7, could each be secured in a variety of
manners. However, it could be possible to employ a manner in which
melting fixation is performed by brazing in the vacuum condition
when producing the vacuum at high temperature (e.g. approx.
800.degree. C.) upon the forming of the vacuum chamber 1b.
[0051] FIG. 2 is a perspective exploded view of a part of the fixed
electrode 4 for explaining an example of the fixed electrode 4
arranged in the vacuum chamber 1b. As shown in FIG. 2, each
electrode member 5 of the fixed electrode 4 is provided with a
fixing hole 5a (three fixing holes in FIG. 2) to fix the fixed
electrode shaft 6 by penetration of the fixed electrode shaft 6.
Then the electrode members 5 are layered so that the fixed
electrode shaft 6 penetrates each fixing hole 5a. In order to make
a space between the electrode members 5, for instance, as shown in
FIG. 2, the ring-shaped spacer 5b having a predetermined thickness
(that is thicker than the electrode member 8 of the movable
electrode 7) which the fixed electrode shaft 6 can penetrate is
provided in each space between the electrode members 5, thereby
making a gap (i.e. a gap having the same thickness as the spacer
5b) between the electrode members 5.
[0052] Here, it is required that each electrode member 5 does not
interfere with the movable electrode shaft 9 and an after mentioned
spacer 8b, etc. when arranged in layers as described above. A
cutting portion 5c etc. is then formed, as appropriate, as shown in
FIG. 2. Further, it is required that the fixed electrode shaft 6
does not interfere with the movable electrode 7 inserted into and
extracted from the fixed electrode 4. For instance, it is
preferable that the fixed electrode shaft stand and be provided at
a position close to an inner circumferential wall surface of the
vacuum chamber 1b.
[0053] FIG. 3 is a schematic view for explaining an example of the
movable electrode 7 arranged in the vacuum chamber 1b. As shown in
FIG. 3, each electrode member 8 of the movable electrode 7 is also
provided with a fixing hole 8a to fix the movable electrode shaft 9
by penetration of the movable electrode shaft 9. Then the electrode
members 8 are layered so that the movable electrode shaft 9
penetrates each fixing hole 8a. In order to make a space between
the electrode members 8, for instance, as shown in FIG. 3, the
ring-shaped spacer 8b having a predetermined thickness (that is
thicker than the electrode member 5 of the fixed electrode 4) which
the movable electrode shaft 9 can penetrate is provided in each
space between the electrode members 8, thereby making a gap (i.e. a
gap 8c having the same thickness as the spacer 8b) between the
electrode members 8.
[0054] Here, it is required that each electrode member 8 does not
interfere with the fixed electrode shaft 6 and the spacer 5b, etc.
when inserted into and extracted from the fixed electrode 4 by
rotation. For example, as shown in FIG. 3, the electrode member 8
having a smaller area than that of the electrode member 5 is
used.
[0055] FIGS. 4 and 5 are schematic views for explaining examples of
change of capacitance by insertion/extraction of the fixed
electrode 4 and the movable electrode 7. As shown in FIG. 4, when
the fixed electrode 4 (each electrode member 5) and the movable
electrode 7 (each electrode member 8) do not overlap each other,
the capacitance of the vacuum capacitor is a minimum capacitance
value. When the movable electrode 7 rotates in an X direction in
FIG. 4 and overlaps the fixed electrode 4, as the overlap area
becomes larger, the capacitance value increases. As shown in FIG.
5, when the overlap area is in a maximum state, the capacitance of
the vacuum capacitor is a maximum capacitance value.
[0056] Each of the electrode member 5 and the electrode member 8
shown in FIGS. 1.about.5 is the flat electrode member, and each
area of both end surfaces of the respective electrode members is
smaller than an area in a cross-section direction of the inside of
the vacuum chamber 1b. For example, it is a semicircular disk, a
sector-shaped disk and a triangular-shaped disk. That is, as long
as the overlap area between the electrode members 5 and 8 can
change according to the rotation of the movable electrode 7 and the
electrode member 8 can rotate inside the vacuum chamber 1b, various
shapes of electrode members can be employed for the electrode
members 5 and 8.
[0057] Although each of the electrode members 5 and 8 in the
drawings is the semicircular disk, namely that its shape is about
half of 360.degree., by the rotation of the movable electrode 7
which is within one revolution, it is possible for the capacitance
of the vacuum capacitor to instantaneously vary within a range from
the minimum capacitance value to the maximum capacitance value.
[0058] Here, in a case where each size of shape of the electrode
members 5 and 8 is over the half of 360.degree., for instance, it
might be difficult to install the movable electrode 7 after
arranging the fixed electrode 4 in the vacuum chamber 1b (namely
that the movable electrode 7 and the fixed electrode 4 might
interfere with each other upon the installation). For this reason,
in the case of the semicircular disk like the electrode members 5
and 8 shown in the drawings, namely, in the case of the size of
shape that is approximately half of 360.degree. or less, it can be
said there is an advantage in assembly.
[0059] FIG. 6 is a schematic view for explaining an example of a
supporting structure of the capacitance control unit 14. In FIG. 6,
the cover member side guide shaft 102i is formed on the surface of
the cover member 102b which is the opposite surface to the surface
facing the vacuum chamber 1b, with the cover member side guide
shaft 102i coaxially arranged with the movable electrode shaft 9.
Then the cover member side guide shaft 102i is loosely inserted in
the control member side guide shaft 14b through the bearing (the
oilless bearing etc.) 14d, and is rotatably supported.
[0060] Here, in order to prevent the bearing 14d from coming out,
for instance, a flange 14e is formed in the control member side
guide shaft 14b. In addition, in order to prevent the coming out of
the capacitance control unit 14 that is loosely fitted onto the
cover member side guide shaft 102i as described above, a screw 14f
etc. is provided at a top portion of the cover member side guide
shaft 102i.
[0061] FIGS. 7 and 8 are schematic views for explaining examples of
a structure in which the magnetic flux .PHI. of the magnetic flux
generating unit 104 is received by the magnetic flux receiving
portion 106b. In FIG. 7, the magnetic drive unit 106 is formed by
arranging the four magnetic flux receiving portions 106b at regular
intervals at the disk member 106a. The capacitance control unit 14
is formed by arranging the four magnetic flux generating units 104
at regular intervals at the outer circumferential edge portion of
the disk member 14a through the magnetic flux generating unit
fixing guide 103. Here, the number of the magnetic flux generating
units 104 set on the magnetic flux generating unit fixing guide 103
is not limited to four, but it is preferable to determine the
number of the magnetic flux generating units 104 and an arrangement
position of the magnetic flux generating units 104 so that the
magnetic flux generated by the whole magnetic flux generating unit
104 is symmetrical with respect to the movable electrode shaft
9.
[0062] The magnetic flux generating unit 104 is arranged so as to
be parallel to the movable electrode shaft 9 with respect to the
magnetic flux receiving portion 10b, namely that the magnetic flux
receiving portion 106b and the magnetic flux generating unit 104
are set through the vacuum partition plate 102a so as to be
positioned in a same line direction which is parallel to the
movable electrode shaft 9. In this way, by setting the magnetic
flux generating unit 104 to the position which is parallel to the
movable electrode shaft 9 with respect to the magnetic flux
receiving portion 106b, the magnetic flux generating unit 104
attracts the magnetic flux receiving portion 106b in the direction
which is parallel to the axis. Thus, even in a case where there
occurs unevenness in a magnetic flux distribution generated from
the whole magnetic flux generating unit 104, a force by which the
movable electrode shaft 9 leans in a radial direction becomes
small.
[0063] Since each magnetic flux receiving portion 106b and each
magnetic flux generating unit 104 are arranged so as to face each
other through the vacuum partition plate 102a of the other side
seal member 102, as shown in FIG. 8, by the magnetic flux .PHI.
generated from the magnetic flux generating unit 104, magnetic
circuit is formed between the magnetic flux receiving portion 106b
and the magnetic flux generating unit 104, and magnetic attraction
is generated. In a case where the capacitance control unit 14 is
rotated in a state in which the magnetic attraction is generated as
described above (i.e. in a case where the magnetic flux generating
unit 104 is moved along the groove portion 112e as shown in FIG. 1
in a state in which the magnetic attraction is generated as
described above), a rotation torque is generated at the magnetic
flux receiving portion 106b in response to the rotation of the
capacitance control unit 14. In a case where the magnetic flux
receiving portion 106b is rotated by the rotation torque generated
according to the magnetic attraction as explained above, when the
rotation torque by the magnetic attraction exceeds the rotation
resistance of the movable electrode shaft 9 etc., the magnetic flux
receiving portion 106b rotates. Therefore, when appropriately
selecting a drive source and the magnetic flux generating unit 104
to control the capacitance control unit 14 with consideration given
to the rotation resistance etc. of the movable electrode shaft 9,
the magnetic flux receiving portion 106b rotates.
[0064] According to the vacuum capacitor of the present invention
as described above, when rotating the capacitance control unit (by
the drive source such as a motor), the magnetic flux generating
unit rotates around an outer circumference of the vacuum casing,
and the magnetic flux receiving portion in the vacuum casing
rotates by the magnetic attraction of the magnetic flux generating
unit in synchronization with the rotation of the magnetic flux
generating unit. That is, since the magnetic flux receiving portion
is fixed to the movable electrode shaft, the movable electrode
secured to the movable electrode shaft rotates in synchronization
with the magnetic flux receiving portion. Hence, the vacuum
capacitor of the present invention does not require any bellows
etc. that is used in the related art vacuum capacitor and expands
and contracts in the axial direction of the vacuum casing. With
this, the life of the vacuum casing (the vacuum chamber etc.) can
be prevented from being shortened.
[0065] Further, by setting the magnetic flux generating unit to the
position which is parallel to the movable electrode shaft with
respect to the magnetic flux receiving portion, even in the case
where the unevenness in the magnetic flux distribution occurs, the
force by which the movable electrode shaft leans in the radial
direction becomes small. For example, as the permanent magnet used
for the magnetic flux generating unit, a plurality of magnets which
are the same in shape and type as each other are used. However,
there is a case where each of the permanent magnets is not strictly
the same as each other due to variations upon manufacturing. Also,
when performing the melting fixation of each structure (each
component or element) of the vacuum casing by brazing in the vacuum
condition, there is a case where a slight difference arises in a
gap between the magnetic flux generating unit and the magnetic flux
receiving portion. As described above, in a case where the magnetic
flux generated between each magnetic flux generating unit and each
magnetic flux receiving portion is not the same, the magnetic flux
distribution in the whole magnetic flux generating unit is not
symmetrical with respect to the movable electrode shaft (the
magnetic flux distribution does not have axial symmetry), and the
unevenness in the magnetic flux distribution might occur. When the
magnetic flux distribution does not have the axial symmetry, the
movable electrode shaft is attracted and loans in a direction in
which the magnetic attraction is strong in the magnetic flux
generating unit with a portion of the movable electrode shaft
touching the diaphragm side being a fulcrum, then there is a
possibility that the rotation resistance of the portion where the
movable electrode shaft and a bearing touch each other will
increase.
[0066] Furthermore, in order to reduce the rotation resistance of
the portion where the movable electrode shaft and the bearing touch
each other, it is conceivable that a ball bearing could be used as
a bearing of the movable electrode shaft. However, when performing
the melting fixation of each component or element of the vacuum
casing by brazing in the vacuum condition at high temperature,
there is a risk that the ball bearing will be melted by the high
temperature or metal powder will appear due to abrasion upon the
rotation. In addition, since a ceramic ball bearing that resists
the high temperature is highly expensive, the vacuum capacitor
becomes expensive. Thus, as a vacuum capacitor that is an
inexpensive vacuum capacitor and has no problem during assembly, a
vacuum capacitor in which the movable electrode shaft is supported
by a slide bearing (a plain bearing) is conceivable.
[0067] In the case where the plain bearing is used as the bearing,
if the movable electrode shaft leans, there is a risk that the
rotation resistance between the bearing and the movable electrode
shaft will increase by a force in the radial direction with a
portion of the bearing touching an edge of the movable electrode
shaft being a fulcrum. Especially when the number of the electrode
members increases in order to increase the capacitance of the
vacuum capacitor, since the movable electrode shaft becomes long,
increase of the rotation resistance due to the lean of the movable
electrode shaft occurs. In the case where the rotation resistance
increases, it is required to increase the rotation torque by the
magnetic attraction between the magnetic flux generating unit and
the magnetic flux receiving portion.
[0068] Thus, like the vacuum capacitor of the present invention, by
setting the magnetic flux generating unit to the position which is
parallel to the movable electrode shaft with respect to the
magnetic flux receiving portion, since the magnetic flux generating
unit attracts the magnetic flux receiving portion in the direction
which is parallel to the axis, even in the case where the
unevenness in the magnetic flux distribution generated from the
whole magnetic flux generating unit occurs, the force by which the
movable electrode shaft leans in the radial direction can be small.
Hence, also in the case where the movable electrode shaft is
supported by the plain bearing, smooth rotation of the movable
electrode shaft can be achieved.
[0069] Further, in the case where the melting fixation is performed
by brazing in the vacuum condition when producing the vacuum at
high temperature for each structure arranged in the vacuum casing,
for instance, it is preferable that the ferromagnetic material be
used for the magnetic flux receiving portion. The magnetic flux
generating unit can be arranged outside the vacuum casing after
performing the melting fixation of each structure in the vacuum
casing by brazing in the vacuum condition. That is, for example, in
a case where the magnetic flux generating unit is exposed to a high
temperature atmosphere during the assembly of the vacuum capacitor,
it is required to provide the magnetic flux generating unit with
consideration given to demagnetization due to the high temperature
(for instance, it is required to use a large-sized magnet).
However, like the magnetic flux generating unit of the present
invention, since it is possible to avoid the exposure to the high
temperature atmosphere during the high temperature vacuum
production process (to avoid the demagnetization due to the high
temperature) and to make full use of the capability which the
magnetic flux generating unit essentially has, the vacuum capacitor
can be prevented from being large in size (or reduction in size of
the vacuum capacitor can be possible).
[0070] In FIG. 1, the fixed electrode is divided into the one side
fixed electrode and the other side fixed electrode, and their lead
connection terminals are positioned at the one side seal member
side rather than the other side seal member side, namely that their
lead connection terminals are positioned apart from the magnetic
flux generating unit. Consequently, even if heat and the magnetic
flux due to application of current are generated upon the current
application to the fixed electrode, it is possible for the magnetic
flux generating unit to be unaffected by the heat and the magnetic
flux. Further, a plurality of the fixed electrode shafts are used.
That is, since the individual fixed electrode shaft is provided for
each of the one side fixed electrode and the other side fixed
electrode, an expansion/contraction phenomenon of the fixed
electrode shaft caused by the heat can be suppressed. In this case,
for instance, change of a gap between the movable electrode and the
fixed electrode can be suppressed, a stable capacitance value can
therefore be obtained.
[0071] Here, in the case where the fixed electrode is divided into
a plurality of the fixed electrodes (for instance, divided in a
direction of the layer arrangement of the electrode members), it is
preferable that each divided fixed electrode be lead to the outside
of the vacuum casing through the lead connection terminal and the
magnetic flux generating unit be unaffected by the heat and the
magnetic flux, even if the heat and the magnetic flux due to
application of current are generated upon the current application
to the fixed electrode.
[0072] Furthermore, in the case where the both end portions of the
movable electrode shaft are formed from the insulator and the
movable electrode is electrically insulated from the outside of the
vacuum casing and for instance the insulative shafts are provided
at both end sides of the movable electrode shaft, a structure of a
movable part (the movable electrode, the movable electrode shaft)
is in a state in which the metal and the insulator touch each
other. Thus there is no metal-metal contact, and an agglutination
phenomenon (junction between the metals in the vacuum condition)
can be avoided. In a case where the insulative shaft has heat
resistance in comparison with the other metal members etc., for
instance, even if the movable part is exposed to the high
temperature atmosphere during the assembly of the vacuum capacitor,
an expansion/contraction phenomenon of the movable electrode shaft
caused by the heat can be suppressed. In this case, for instance,
change of the gap between the movable electrode and the fixed
electrode can be further suppressed, and the more stable
capacitance value can be obtained.
[0073] Moreover, also in the case where the movable electrode shaft
is rotatably supported using the adjustment diaphragm, since the
movable electrode shaft is forced in the direction of the seal
member which is opposite to the adjustment diaphragm, for instance,
change of the gap between the movable electrode and the fixed
electrode can be suppressed, and the more stable capacitance value
can be obtained. Additionally, by forming the portion of the
adjustment diaphragm which touches the movable electrode shaft into
a small shape (by forming the pointed shaped portion or an acute
shaped portion), the rotation resistance of the movable electrode
shaft can be reduced. This can allow a decrease in driving force of
the vacuum capacitor, e.g. a decrease in consumption of drive
energy to rotate the capacitance control unit, and also a reduction
in size of the vacuum capacitor.
[0074] Although only the embodiment described above in the present
invention has been explained in detail, it is obvious to a person
skilled in the art that modifications and variations of the
embodiment can be possible within a scope of technical idea of the
present invention. It is right that these modifications and
variations are included in the scope of the claims.
EXPLANATION OF REFERENCE
[0075] 1 . . . vacuum capacitor [0076] 1a . . . vacuum casing
[0077] 1b . . . vacuum chamber [0078] 2, 102 . . . seal member
[0079] 4 . . . fixed electrode [0080] 5, 8 . . . electrode member
[0081] 6 . . . fixed electrode shaft [0082] 7 . . . movable
electrode [0083] 9 . . . movable electrode shaft [0084] 11a . . .
adjustment diaphragm [0085] 106b . . . magnetic flux receiving
portion [0086] 104 . . . magnetic flux generating unit [0087] 14 .
. . capacitance control unit
* * * * *